This disclosure relates to solid oxide fuel cells having metallic supports. Solid oxide fuel cells are commonly known and used for generating electricity. For example, conventional solid oxide fuel cells typically a cell having an anode, a cathode, and an electrolyte between the anode and the cathode. A support structure mechanically supports the cell and may also serve to supply reactant gas and conduct electric current to an external circuit.
One problem associated with such support structures is that the operating environment is severely corrosive. For instance, the fuel cell may be operated at elevated temperatures and the support structure may be exposed to a dual exposure environment of a reactant gas oxidant (e.g., air) on one side and a reactant gas fuel (e.g., hydrogen) on another side. This dual exposure produces an oxidizing environment that can rapidly oxidize common alloys that are used for the support structure, such as stainless steel. Oxidation of the support structure may diminish the mechanical strength and electrical conductivity.
Another problem associated with conventional solid oxide fuel cells is possible damage to the fuel cell from thermal cycling (e.g., ON/OFF cycles). The electrode is typically a ceramic material having a nominal coefficient of thermal expansion (“CTE”) of about 11×10−6/° C., which is considerably different than most alloys. Stainless steel, however, also has a nominal CTE of about 11×10−6/° C. and thereby mitigates thermal stresses between the electrode and the support structure due to thermal cycling. Although alloys with better resistance to oxidation than stainless steel are known, such alloys cannot be directly substituted for the stainless steel because the CTE mismatch with the ceramic material of the electrode may cause damage to the fuel cell under thermal cycling.